In the prior art, it is desirable to administer an immunopotentiator for activating the immune response of a host as prophylaxis against an impending infection, for the management of a disease in progress, to potentiate the immune response against tumor cells, or for restoring the immune response in immunodepressed states. Generally, the immunopotentiators used enhance the immune system including, but are not limited to, increasing macrophage activity, improving T cell response, increasing NK cell activity, increasing B cell response, increasing complement activity, for inducing interferon production, increasing granulocyte function, and the like.
The immunopotentiators of the prior art administered to a host for stimulating the immune response broadly includes immunopotentiators of synthetic origin, immunopotentiators of natural origin, and immunopotentiators derived from biological sources. While, the use of immunopotentiators represents a valuable contribution to the prior art, serious disadvantages often are associated with their use. For example, while one of the aims of using an immunopotentiator is to activate and achieve an immune response of a durable and high level, the immunopotentiator in many instances quickly dissipates necessitating a number of repeated doses, for example, as practiced in the management of neoplastic diseases, for producing the intended results. Another shortcoming frequently observed is the administration of the immunopotentiator in a single and repeated doses does not supply enough immunopotentiator for stimulating the immune system, and the immunopotentiator administered often causes toxic effects such as fever, malaise, and the like.
In other embodiments the prior art resorted to carriers, such as oily emulsions in depot form for administering the immunopotentiator for obtaining the desired benefit, but this too entailed drawbacks. For example, the oils used are not easily metabolized, they may be incompatible with the host, and they can give rise to sever toxic reactions. These affects tend to defeat their use. Then too, the previous methods of administration expose the tissues of the host to unknown quantities of immunopotentiator which can be irritating and react with the tissue, producing an unwanted inflammatory response that is of unknown severity and duration. The use of oily depots, which are not immunopotentiators, but are intended to function as an in vivo repository, are replete with shortcomings. That is, depots do not keep their integrity and accordingly they do not maintain a predictable repository effect. By losing their integrity, they allow large numbers of inflammatory cells to accumulate at the depot site thereby producing unwanted irritation and often granulamatous lesions. Depots previously known to the art are made of materials that spread and diffuse throughout the area in which they are injected and they are not conducive for the controlled release of immunopotentiator over time.
It will be appreciated by those versed in the art that if a method is made available for delivering an immunopotentiator to enhance the immune response, which method is free of the high single dose or the multiple dose disadvantages known to the prior art, such a method would represent a valuable contribution to the art. Likewise, it will be appreciated by those versed in the art, that if a method is made available which avoids giving rise to significant local inflammation, such a method also would be a useful contribution to the art. Similarly, it will be appreciated that if a method is provided which accelerates the appearance of the immune response at protective levels, such a method would also be an improvement in the art.